JP3962300B2

JP3962300B2 - Aluminum oxide coated tool

Info

Publication number: JP3962300B2
Application number: JP2002235535A
Authority: JP
Inventors: 敏夫石井; 広志植田; 有三福永
Original assignee: Hitachi Tool Engineering Ltd
Current assignee: Moldino Tool Engineering Ltd
Priority date: 2002-08-13
Filing date: 2002-08-13
Publication date: 2007-08-22
Anticipated expiration: 2022-08-13
Also published as: JP2004074324A

Description

【０００１】
【発明の属する技術分野】
本願発明は、切削用及び耐摩耗用の酸化アルミニウム被覆工具に関する。
【０００２】
【従来の技術】
一般に、被覆工具は超硬質合金、高速度鋼、特殊鋼よりなる基体表面に硬質皮膜を化学蒸着法（以下、ＣＶＤ法と称する。）や物理蒸着法により成膜することにより作製される。このような被覆工具は皮膜の耐摩耗性と基体の強靭性とを兼ね備えており、広く実用に供されている。特に、高硬度材を高速で切削する場合に、切削工具の刃先温度は１０００℃前後まで上がるとともに、このような高温で被削材との接触による摩耗や断続切削等の機械的衝撃に耐える必要があり、耐摩耗性と強靭性及び耐熱性を兼ね備えた被覆工具が重宝されている。硬質皮膜には、耐摩耗性と靭性とが優れる周期律表４ａ、５ａ、６ａ族金属の炭化物、窒化物、炭窒化物からなる非酸化膜や耐酸化性が優れる酸化膜が単層或いは多層膜として用いられる。非酸化膜では例えばＴｉＣ、ＴｉＮ、Ｔｉ（ＣＮ）が利用され、酸化膜では特にκ型酸化アルミニウム（以下、κ−Ａｌ_２Ｏ_３と称する。）やα型酸化アルミニウム（以下、α−Ａｌ_２Ｏ_３と称する。）が利用されている。上記非酸化膜の欠点は酸化され易いことであり、この欠点を補うため、これらの非酸化膜の上に耐酸化性が優れる酸化アルミニウムを形成することにより非酸化膜の酸化を防止することが一般に行われている。この非酸化膜／酸化アルミニウム膜の多層膜構造の欠点は非酸化膜と酸化アルミニウム膜との間の密着性が低いこと、或いは高温で機械強度が安定しないことである。このようなα−Ａｌ_２Ｏ_３膜の欠点を解消するため、特開平０９−２９５１２号公報及び特開平０８−２７６３０５号公報では、α−Ａｌ_２Ｏ_３層の下地層となる結合層にＴｉ（ＣＮＯ）を用い、この結合層の表面形態が等軸又は針状の結晶粒となっていることが開示されている。更に、特許第３２５０１３４号公報では、酸化アルミニウム層の下地層としてＴｉ（ＣＮＯ）を用い、該下地層の表面状態を先鋭化針状結晶とすることにより、酸化アルミニウム層とＴｉ（ＣＮＯ）からなる下地層との密着性を向上しようとする事例を開示している。しかし、これらＴｉ系の酸炭窒化物単独から成る結合層ではその表面にα−Ａｌ_２Ｏ_３膜との密着性を高める効果が期待される突起が形成し難く、このためその化学蒸着装置内全体で結合層の表面にα−Ａｌ_２Ｏ_３膜を密着性良く成膜することは困難であった。一方、比較的容易に突起を形成しやすい結合層としてＴｉとＡｌの両者を含有した結合層も提案されている。すなわち、特開平０３−１３８３６８号公報では、炭化物結合焼結体からなる基体上にα−Ａｌ_２Ｏ_３層とκ−Ａｌ_２Ｏ_３層とを積層する場合において、（ＡｌＴｉ）（ＯＣ）からなる２種類の結合層（α変態層、κ変態相）を使い分ける事により、純粋なα−Ａｌ_２Ｏ_３層とκ−Ａｌ_２Ｏ_３層との堆積の制御を可能とした事例が開示されている。
【０００３】
【発明が解決しようとする課題】
しかし、これらの結合層が酸素を含有することによる酸化膜の生成基点と、突起構造による密着性が強化されるアンカー効果の両機能が１つの層により担われているため、例えば突起組織のみを強化することによりα−Ａｌ_２Ｏ_３の密着性を更に高める、或いは結合層の酸素含有量を高めることによりα−Ａｌ_２Ｏ_３が安定して成膜されるようにする等の調整が難しいという欠点がある。また、ＴｉとＡｌの両者を含有した結合層では酸素含有量の制御が難しく、酸素が少ないとその表面にα−Ａｌ_２Ｏ_３よりもむしろκ−Ａｌ_２Ｏ_３が生成されやすくなり、酸素量が多すぎると結合層自体が機械的に脆くなり、結合層の部分からα−Ａｌ_２Ｏ_３が剥離しやすくなる欠点がある。例えば、現状の量産型のＣＶＤ装置では内径２６０ｍｍ×高さ７００ｍｍの範囲内に約５０００個のインサート工具をセットし成膜するが、装置内全体のインサート工具にα−Ａｌ_２Ｏ_３を安定して成膜するために、酸素量を上げると、装置内の一部が酸素量過剰になりα−Ａｌ_２Ｏ_３が剥がれやすくなり、一方α−Ａｌ_２Ｏ_３の密着性を高めるため酸素量を下げると、ＣＶＤ装置内に多数個セットしたインサート工具の一部にα−Ａｌ_２Ｏ_３が成膜されずκ−Ａｌ_２Ｏ_３が成膜されてしまう欠点があらわれる。上記問題を踏まえて、本発明が解決しようとする課題は、ＣＶＤ装置内全体で安定して下地の非酸化膜との密着性が優れるα−Ａｌ_２Ｏ_３を主とする酸化膜が成膜でき、その結果、品質のばらつきが少なく優れた特性を有する酸化アルミニウム被覆工具を提供することである。
【０００４】
【課題を解決するための手段】
本発明者らは上記課題を解決するために、基体表面に周期律表の４ａ、５ａ、６ａ族金属の炭化物、窒化物、炭窒化物、酸化物、酸炭化物、酸窒化物及び酸炭窒化物のいずれか１種の単層皮膜又は２種以上からなる多層皮膜が形成され、該皮膜表面に結合層を介してα型酸化アルミニウムを主とする酸化膜が形成されている酸化アルミニウム被覆工具において、該結合層が少なくとも基体側から順にＴｉ及びＡｌの酸化物、酸炭化物、酸窒化物又は酸炭窒化物からなる層とα型酸化アルミニウムを主とする酸化膜側に形成されたＴｉの酸化物、酸炭化物、酸窒化物又は酸炭窒化物からなる層とにより構成されており、該結合層表面が略膜厚方向に突き出た多数の突起を有していることを特徴とする酸化アルミニウム被覆工具である本発明を適用することによりα−Ａｌ_２Ｏ_３を主とする酸化膜とその下地である非酸化膜との間にあり両膜に直接接触する結合層を複層構造にし、各層にアンカー効果による密着性強化機能と酸化膜生成機能とを別個に担わせることにより、下地非酸化膜との密着性が優れるα−Ａｌ_２Ｏ_３を主とする酸化膜がＣＶＤ装置内全体で安定して成膜されるようになり、上記問題点が解消する。また、本発明のα−Ａｌ_２Ｏ_３を主とする酸化膜とは、８０ｖｏｌ％以上のα−Ａｌ_２Ｏ_３を含み、残りがκ−Ａｌ_２Ｏ_３、γ型酸化アルミニウム、θ型酸化アルミニウム、δ型酸化アルミニウム、χ型酸化アルミニウム等、他の構造の酸化アルミニウム、酸化ジルコニウム等の酸化物からなる混合組織のものをいう。
【０００５】
第１に、結合層を二層に分けることによりα−Ａｌ_２Ｏ_３を主とする酸化膜との密着性を強化する機能とα−Ａｌ_２Ｏ_３が生成されやすくする機能とが分離でき各機能を別個に制御することができ下地非酸化膜との密着性が優れるα−Ａｌ_２Ｏ_３を主とする酸化膜がＣＶＤ装置内全体で安定して成膜できるようになる。即ち、Ｔｉ及びＡｌの酸化物、酸炭化物、酸窒化物又は酸炭窒化物から成る層が略膜厚方向に突き出た多数の突起を有する組織から成っていることにより、いわゆるアンカー効果等により上層のα−Ａｌ_２Ｏ_３を主とする酸化膜の密着性を高めることができ、しかも結合層の表面側にＴｉの酸化物、酸炭化物、酸窒化物又は酸炭窒化物から成る層を形成しその酸素含有量を最適化することによりＣＶＤ装置内全体でα−Ａｌ_２Ｏ_３が安定して成膜されるようになる。
【０００６】
第２に、結合層内に略膜厚方向に突き出た多数の突起を有する組織が含有されているため結合層の表面も略膜厚方向に突き出た多数の突起を有する組織になる。尚、上記のように結合層を層別に区分けしたのは成膜過程から区分けしたものであり、成膜後の皮膜を観察した時には外観上からは明確に区分け出来ないことが多い。この場合も、エネルギー分散型Ｘ線分析装置（以下、ＥＤＸと称する。）や電子プローブマイクロアナライザー装置（以下、ＥＰＭＡと称する。）を用いてＡｌとＴｉの分布を膜厚方向に分析した時、ある膜厚領域にＡｌ成分が多く検出され、他の膜厚領域ではＡｌがほとんど検出されないことから結合層が上記のような複層構造で形成されていることがわかる。特に、結合層の厚さが数１００ｎｍであり、結合層を層別に明確に分析することが出来ない場合はＡｌとＴｉを膜厚方向に線分析した時、Ａｌ／Ｔｉ比がある膜厚領域で明確に高くなることにより上記のような層状に結合層が形成されていることがわかる。透過電子顕微鏡（以下、ＴＥＭと称する。）に内蔵されたＥＤＸを用いて数１０ｎｍの微少領域を分析する場合はＴＥＭ用の薄い試料を作製する時にイオンミリング等で掘られたＡｌやＴｉ、Ｗ、Ｃｏ等の元素がＴＥＭ試料に再付着する。この時、ＡｌやＴｉは膜中から、ＷやＣｏは超硬合金製基体から再付着する。このためＡｌやＴｉ等の有無が明確に識別出来ないことがある。この時も上記と同様に膜厚方向に異なる位置でＡｌ／Ｔｉ比を分析することにより結合層が上記のような層状に形成されていることがわかる。この場合、ＴＥＭ試料作製時の付着により検出されるＡｌ／Ｔｉ比量、即ちＡｌ／Ｔｉ比のゼロ点はＴｉＣＮ等の本来Ａｌを含有していない下地非酸化膜のＡｌ／Ｔｉ比を測定することにより得られる。
【０００７】
第３に、本発明は、該結合層が少なくとも基体側から順にＴｉの酸化物、酸炭化物又は酸窒化物からなる層、Ｔｉ及びＡｌの酸化物、酸炭化物、酸窒化物又は酸炭窒化物からなる層及びＴｉの酸化物、酸炭化物、酸窒化物又は酸炭窒化物からなる層の３層により構成されている。下地の非酸化膜の上にＴｉと酸素を含有した皮膜から成る第１層を介してＴｉ、Ａｌ及び酸素を含有する第２層を成膜することにより下地の非酸化膜と第２層間の密着性が更に高まり、結合層と下地非酸化膜の間に更に高い密着性が得られる。また、成膜ガスとして、より少ない酸素ガス供給量で略膜厚方向に突き出た多数の突起を有する第２層の組織が安定して成膜出来るようになり第２層の高い機械強度と上層の酸化膜との密着性が更に高まり、更に優れた工具特性を有する被覆工具が得られる。
【０００８】
第４に、本発明は、該結合層表面の略膜厚方向に突き出た多数の突起が鉤型に屈曲している。鉤型に屈曲させることにより、結合層とα−Ａｌ_２Ｏ_３を主とする酸化膜との間に更に高い密着性が得られ、更に優れた工具特性を有する被覆工具が得られる。
【０００９】
第５に、本発明は、該結合層表面の略膜厚方向に突き出た多数の突起の先端が丸くなっている。先端が丸くなっているとは先端が先鋭でなく緩やかな曲面で形成されていることをいい、突起先端の断面積が大きくなり突起自体の機械強度が高まり、結合層とα−Ａｌ_２Ｏ_３を主とする酸化膜との間に更に高い密着性が得られ、更に優れた工具特性を有する被覆工具が得られる。
【００１０】
第６に、本発明は、結合層の少なくとも一部の層の断面が基体と略垂直方向に細長い結晶粒郡からなっていることより、結合層の表面が突起に富みアンカー効果等によりα−Ａｌ_２Ｏ_３を主とする酸化膜の密着性を更に高めることができる。層の断面が基体と略垂直方向に細長い結晶粒郡からなっていることはＳＥＭ又はＴＥＭで観察することにより確認できる。
【００１１】
第７に、本発明は、α−Ａｌ_２Ｏ_３を主とする酸化膜の表面に少なくとも有色のＴｉ、Ｚｒ又はＨｆの窒化物、炭化物、炭窒化物、酸化物、酸窒化物、酸炭化物、酸炭窒化物のいずれか１種の単層皮膜又は２種以上からなる多層皮膜が形成されており、工具表面の摺動性がより高まり更に優れた工具特性が得られるとともに、有色の皮膜で工具の外層部分を構成することになり工具として使用済みの有無が容易に判別出来るようになる。
【００１２】
第８に、本発明は、上記皮膜を形成した後に少なくとも刃先部周辺の最外層の一部が除去され、α−Ａｌ_２Ｏ_３を主とする酸化膜が露出させることにより、被削材との接触頻度が高い刃先部の少なくとも１部が耐酸化性と耐溶着性とが特に優れているα−Ａｌ_２Ｏ_３を主とする酸化膜で構成されていることになり被削材と溶着することが特に少なくなり特に優れた切削耐久特性が実現できる。
【００１３】
本発明における被覆方法には既知の成膜方法を適用することが可能である。例えば、通常の熱化学蒸着法、プラズマを付加した化学蒸着法等を用いることができる。用途は切削工具に限るものではなく、α−Ａｌ_２Ｏ_３を主とする酸化膜を含む単層或いは多層の硬質皮膜により被覆された耐摩耗材や金型、溶湯部品等でも良い。酸化膜はα−Ａｌ_２Ｏ_３単層に限るものではなく、α−Ａｌ_２Ｏ_３が主であれば、他の酸化物、例えばα−Ａｌ_２Ｏ_３とκ−Ａｌ_２Ｏ_３との混合膜や、γ型酸化アルミニウム、θ型酸化アルミニウム、δ型酸化アルミニウム、χ型酸化アルミニウム等、他の構造の酸化アルミニウムとの混合膜或いはα−Ａｌ_２Ｏ_３と酸化ジルコニウム等他の酸化物との混合膜であっても同様の作用効果を得ることが可能である。次に、本発明の被覆工具を実施例により具体的に説明するが、これら実施例により本発明が限定されるものではない。
【００１４】
【発明の実施の形態】
（実施例１）
本発明例１としてまず、ＷＣ：７２質量％、ＴｉＣ：８質量％、（ＴａＮｂ）Ｃ：１１質量％、Ｃｏ：９質量％の成分組成よりなるＪＩＳ規格ＣＮＭＧ１２０４０８形状の切削工具用超硬合金基体２００個を万遍なくセットした内径２６０ｍｍ、高さ２５ｍｍのカーボン製トレーを２３段、縦方向に積み上げ、ＣＶＤ反応装置内にセットした。尚、成膜の安定性を確保するため、有効な２３段のトレーの上下にダミートレーをそれぞれ２段と３段セットした。そして、Ｈ_２キヤリヤーガスとＴｉＣｌ_４ガスとＮ_２ガスとを原料ガスに用いて０．５μｍ厚さのＴｉＮ膜を９００℃で形成後、Ｈ_２キャリヤーガスとＴｉＣｌ_４ガス、Ｎ_２ガス、ＣＨ_３ＣＮガスを原料ガスに用いて６μｍ厚さのＴｉＣＮ膜を８９０℃で形成した後、１０００℃でＨ_２キヤリヤーガスとＴｉＣｌ_４ガス、ＣＨ_４ガス、Ｎ_２ガスとを原料ガスに用いてＴｉ（ＣＮ）膜を１５分間成膜した。その後、Ｔｉ（ＣＮ）の成膜に用いたのと同じ構成からなるガス郡にＣＯガスとＡｌＣｌ_３ガスとを追加して（ＴｉＡｌ）（ＣＮＯ）膜を１０００℃で１０分間成膜し、そのまま更にＨ_２キヤリヤーガスとＴｉＣｌ_４ガス、ＣＨ_４ガス、Ｎ_２ガス及びＣＯ_２ガスとＣＯガスとを原料ガスに用いてＴｉ（ＣＮＯ）膜を７分間成膜することにより（ＴｉＡｌ）（ＣＮＯ）とＴｉ（ＣＮＯ）との２層からなる結合層を成膜した。その後、Ｈ_２キャリヤーガス、ＡｌＣｌ_３ガス、ＣＯ_２ガスを原料ガスに用いて４μｍ厚さのＡｌ_２Ｏ_３膜を１０２０℃で形成し、更に、Ｈ_２キヤリヤーガスとＨｆＣｌ_４ガス及びＮ_２ガスとを原料ガスに用いて厚さ１μｍのＨｆＮ膜を１０５０℃で形成した後、室温まで冷却した。次に、ＣＶＤ装置から取り出した試料の刃先部のホーニング部分周辺をラバー砥石により研磨することによって、内層のＡｌ_２Ｏ_３膜を露出させ本発明の酸化膜被覆工具を作製した。
【００１５】
作製した本発明例の皮膜を理学電気製のＸ線回折装置（ＲＵ−２００ＢＨ）でＸ線源にＣｕＫα１線を用いて２θ−θ走査法によりＸ線回折図形を測定した結果、有効トレーの最上段２３段目の内側、外側の試料番号を２３Ａ、２３Ｂ、中段１２段目の内側、外側の試料位置番号を１２Ａ、１２Ｂ及び最下段１段目の内側、外側の試料位置番号を１Ａ、１Ｂの何れの位置にセットした試料もα−Ａｌ_２Ｏ_３のＸ線回折ピークのみが検出されκ−Ａｌ_２Ｏ_３等のピーク強度は検出限界以下であった。このことから、有効トレー内全体の試料にα−Ａｌ_２Ｏ_３が成膜されたと考えられる。
【００１６】
本発明例を１７度傾けて研磨し基体表面からα−Ａｌ_２Ｏ_３膜迄を倍率１０００倍で撮影した光学顕微鏡写真を図１に、またその模式図を図２に示す。図１、２には、超硬合金製基体１の表面にＴｉＮ膜２とＴｉ（ＣＮ）膜３が形成され、その上に結合層４を介してα−Ａｌ_２Ｏ_３膜５が形成されていることが示されている。図１、２より、結合層４の表面から多数の突起がα−Ａｌ_２Ｏ_３膜５側に突き出ておりα−Ａｌ_２Ｏ_３膜５中に食い込んでいることがわかる。また、図３は上記試料の結合層４とα−Ａｌ_２Ｏ_３膜５間の界面近傍をＳＥＭにより倍率５０００倍で撮影したもの、図４はその模式図である。図３、４より、結合層）の表面に略膜厚方向に多数の突起が突き出ており、しかも先端が鉤型に屈曲していることが、特に図３、４の左から３番目と右から３番目の突起から良くわかる。また、これらの突起の先端が先鋭ではなく丸くなっていることがわかる。
【００１７】
本発明例の成膜面の膜断面を厚さ２０μｍ以下に研磨した後、更に、イオンミリングにより膜断面の厚さを極端に薄くしてＴＥＭ観察用の試料を作製した。そして日立製作所製のＴＥＭ（Ｈ−８００）を用い、加速電圧２００ｋＶの条件でＴｉ（ＣＮ）膜部とＡｌ_２Ｏ_３膜部の間にある薄い結合層部を同定した後、ＴＥＭ内蔵のＮＯＲＡＮ社製のＥＤＸで元素分析した結果、結合層は２層に分離でき、基体側の第１層はＴｉとＡｌ、第２層はＴｉのみから形成されていることがわかった。尚、ＥＤＸ分析のため軽元素であるＣ、Ｎ、Ｏは分析できなかった。また、ＴＥＭ試料作製時に発生した再付着物量を求めるため結合層直下のＴｉＣＮ皮膜中央部でＷとＣｏ量及びＡｌ_２Ｏ_３膜直上のＨｆＮ膜中央部でＴｉとＡｌ量とを測定し、その値を再付着物量として結合層部の分析値から差し引いた。また、上記ＴＥＭ観察の結果、結合層中でＡｌが多い膜厚領域は断面が略膜厚方向に細長い結晶粒郡で形成されておりその一部が膜厚方向に突き出し突起が形成されていること、そして結合層の表面にＴｉは分析されるがＡｌは再付着物量分しか分析されない膜厚領域がありこの領域は粒状の結晶粒郡から形成されていることが観察された。
【００１８】
（実施例２）
本発明例２としてまず、本発明例１と同じ材質と形状の基体を本発明例１と同様にＣＶＤ反応装置内に設置し、本発明例１と同じ条件でＴｉＮ膜と２種類のＴｉ（ＣＮ）膜を成膜した。その後、２番目のＴｉ（ＣＮ）の成膜に用いたのと同じ構成からなるガス郡にＣＯガスを追加してＴｉ（ＣＮＯ）膜を１０００℃で１５分間成膜した後、更にＡｌＣｌ_３ガスを追加して（ＴｉＡｌ）（ＣＮＯ）膜を１０分間成膜し、そして更にＨ_２キヤリヤーガスとＴｉＣｌ_４ガス、ＣＨ_４ガス、Ｎ_２ガス及びＣＯ_２ガスとＣＯガスとを原料ガスに用いてＴｉ（ＣＮＯ）膜を７分間成膜することによりＴｉ（ＣＮＯ）−（ＴｉＡｌ）（ＣＮＯ）−Ｔｉ（ＣＮＯ）の３層からなる結合層を成膜した。その後、本発明例１と同じ条件でＡｌ_２Ｏ_３膜をした後、更に、Ｈ_２キヤリヤーガスとＣＨ_４ガス、Ｎ_２ガス及びＺｒＣｌ_４ガスとを原料ガスに用いて厚さ１μｍのＺｒ（ＣＮ）膜を１０２０℃で形成した後、室温まで冷却した。次に、ＣＶＤ装置から取り出した試料の刃先部のホーニング部分周辺をダイヤモンド砥粒とブラシにより研磨することによって内層のＡｌ_２Ｏ_３膜を露出させ本発明例２を作製した。本発明例２のＸ線回折図形を本発明例１と同じ方法で試料位置番号：２３Ａ、２３Ｂ、１２Ａ、１２Ｂ、１Ａ、１Ｂの試料を測定した結果、全てα−Ａｌ_２Ｏ_３のＸ線回折ピークのみが検出されκ−Ａｌ_２Ｏ_３等のピーク強度は検出限界以下であった。本発明例１と同様に有効トレー内全体の試料にα−Ａｌ_２Ｏ_３が成膜された。また、本発明例１と同様に本発明例２の研磨面を光学顕微鏡とＳＥＭで観察した結果、結合層の表面に略膜厚方向に多数の突起が突き出ており、しかもその多くの先端が鉤型に屈曲しており、突起の先端も丸くなっていることが確認された。本発明例２の成膜面の膜断面を本発明例１と同様にＴＥＭ−ＥＤＸにより分析した結果、結合層は３層に分離でき、基体側の第１層はＴｉのみ、第２層はＴｉとＡｌ、第３層はＴｉのみから形成されていることがわかった。軽元素であるＣ、Ｎ、Ｏは本発明例１と同様に分析できなかった。結合層の第１層は粒状の結晶粒郡で形成されており、第２層は断面が略膜厚方向に細長い結晶粒郡で形成されておりその１部が膜厚方向に突起を形成しており、第３層は再び粒状の結晶粒郡で形成されていることが観察された。
【００１９】
（実施例３）
比較例３としてまず、結合層の構造の差異によるα−Ａｌ_２Ｏ_３を主とする酸化膜の密着性及び切削特性への影響を明らかにするために、本発明例１と同じ材質と形状の基体を本発明例１と同様にＣＶＤ反応装置内に設置し、本発明例１と同じ条件でＴｉＮ膜と２種類のＴｉ（ＣＮ）膜を成膜した。その後、Ｈ_２キャリヤーガスとＴｉＣｌ_４ガスとＣＨ_４ガスを原料ガスに用い１０１０℃で５〜３０分間反応させＴｉＣ膜を成膜した後、そのままＴｉＣｌ_４ガスとＣＨ_４ガスとを止めＨ_２キャリヤーガスとＣＯ_２ガスとを１５分間流し既に成膜したＴｉＣ膜表面を酸化することにより結合層を作製した。その後、本発明例１と同じ条件で４μｍ厚さのＡｌ_２Ｏ_３膜と厚さ１μｍのＨｆＮ膜を形成した後室温まで冷却し、比較例３を作製した。比較例３のＸ線回折図形を本発明例１と同じ方法で試料位置番号：２３Ａ、２３Ｂ、１２Ａ、１２Ｂ、１Ａ、１Ｂの試料を測定した結果、全てα−Ａｌ_２Ｏ_３のＸ線回折ピークのみが検出されκ−Ａｌ_２Ｏ_３等のピーク強度は検出限界以下であった。有効トレー内全体の試料にα−Ａｌ_２Ｏ_３が成膜されたと考えられる。比較例３の研磨面を光学顕微鏡とＳＥＭで観察した結果、結合層の表面は粒状の結晶粒からなっており穏やかな曲面が形成されており、本発明１、本発明例２のような突起は形成されていないことがわかった。比較例３の皮膜断面をＴＥＭで観察した結果、基体表面から順にＴｉＮ、Ｔｉ（ＣＮ）、ＴｉＣ、結合層、Ａｌ_２Ｏ_３の各層が形成されていること、また、結合層は粒状の結晶粒から構成され膜厚方向に細長い結晶粒郡からは構成されていないことが判明した。また、結合層の組成をＥＤＸで分析した結果、Ｔｉのみが検出されＡｌは再付着量分しか検出されず、結合層は金属成分としてＴｉのみを含有しておりＡｌは含有していないことがわかった。
【００２０】
（実施例４）
比較例４として、結合層の構造の差異によるα−Ａｌ_２Ｏ_３を主とする酸化膜のＣＶＤ装置内全体での安定成膜性及び切削特性への影響を明らかにするために、本発明例１と同じ材質と形状の基体を本発明例１と同様にＣＶＤ反応装置内に設置し、本発明例１と同じ条件でＴｉＮ膜と２種類のＴｉ（ＣＮ）膜を成膜した。その後、Ｔｉ（ＣＮ）の成膜に用いたのと同じ構成からなるガス郡にＣＯガスとＡｌＣｌ_３ガスとを追加して（ＴｉＡｌ）（ＣＮＯ）膜を１０分間成膜した。上記の（ＴｉＡｌ）（ＣＮＯ）単層からなる結合層の表面に直接、本発明例１と同じ条件で４μｍ厚さのＡｌ_２Ｏ_３膜と厚さ１μｍのＨｆＮ膜を形成した。そして、本発明例１と同じ条件でホーニング部分周辺を研磨することにより内層のＡｌ_２Ｏ_３膜を露出させて比較例４を作製した。比較例４のＸ線回折図形を本発明例１と同じ方法で試料位置番号：２３Ａ、２３Ｂ、１２Ａ、１２Ｂ、１Ａ、１Ｂの試料を測定した結果、試料位置番号：２３Ａ、２３Ｂ、１２Ａ、１Ｂの試料はα−Ａｌ_２Ｏ_３のＸ線回折ピークのみが検出されκ−Ａｌ_２Ｏ_３等のピーク強度は検出限界以下であったが、試料位置番号：１２Ａ、１Ａの試料はκ−Ａｌ_２Ｏ_３のピークが大部分であり、α−Ａｌ_２Ｏ_３は（１０４）のピークが弱く検出されるだけであった。比較例４では安定してα型酸化アルミニウムを主とする酸化膜が製作できないことがわかる。比較例４の研磨面を光学顕微鏡とＳＥＭで観察した結果、結合層の表面には略膜厚方向に多数の突起が突き出てはいるが、これらの突起先端は鋭くなっており丸くないことが確認された。比較例４の成膜面の膜断面を本発明例１と同じ条件でＴＥＭ観察した結果、結合層はＴｉとＡｌの両者を含有する単一層から成っておりその上にＴｉのみからなる第２層は形成されていないことがわかった。
【００２１】
次に、本発明例１、本発明例２の条件で製作した切削工具と比較例３、４の条件で製作した工具の各５個を用いて、以下の切削条件で１分間と１０分間連続切削試験した後に酸化アルミニウム皮膜の剥離状況を倍率２００倍の光学顕微鏡により観察し、評価した。切削諸元は、被削材：ＦＣＤ７００、切削速度：３００ｍ／ｍｉｎ、送り：０．３ｍｍ／ｒｅｖ、切り込み：２．０ｍｍ、水溶性切削油使用である。この切削試験の結果、比較例３は１分間切削後にすくい面の酸化アルミニウム皮膜が大きく剥離したのに対して、本発明例１、本発明例２と比較例４はいずれも１分間連続切削後も酸化アルミニウム皮膜の剥離が見られず、下地膜に対する酸化アルミニウム膜の密着性が優れていることが判明した。更に１０分間連続切削した後に本発明１、２と比較例４を観察すると、κ−Ａｌ_２Ｏ_３のＸ線回折ピークが強く現れた比較例４の試料位置番号：１２Ｂ、１Ｂの試料はすくい面の酸化アルミニウム皮膜中に大きくクラックが発生しており、所々で皮膜が大きく剥離していることが観察された。これは、１０分間の連続切削により皮膜表面の温度が上がり、κ−Ａｌ_２Ｏ_３の一部がα−Ａｌ_２Ｏ_３に変態し、体積が収縮したためクラックが発生し、そこを起点にして膜が剥離したと考えられる。そして残った試料を更に１０分間連続切削した結果、比較例４の試料位置番号：２３Ａ、２３Ｂ、１２Ａ、１Ｂの試料は、すくい面が剥離したのに対して、本発明例１、本発明例２はいずれの試料も剥離しなかった。本発明例１、本発明例２はＣＶＤ装置内全体で下地膜との密着性と耐熱・耐クラック性が優れた酸化アルミニウム膜が形成されていることがわかる。
【００２２】
【発明の効果】
上述のように、本発明によれば、下地の非酸化膜との密着性が優れるα−Ａｌ_２Ｏ_３を主とする酸化膜がＣＶＤ装置内全体で安定して成膜できるようになり、その結果、品質のばらつきが少なく、多層膜間の密着性と耐熱・耐クラック性とが優れ、優れた工具特性有し、工具寿命の長い優れた酸化アルミニウム被覆工具が実現できる。
【図面の簡単な説明】
【図１】図１は、本発明例の組織写真を示す。
【図２】図２は、図１の模式図を示す。
【図３】図３は、図１の結合膜とα−Ａｌ_２Ｏ_３膜間の界面近傍組織写真を示す。
【図４】図４は、図３の模式図を示す。
【符号の説明】
１超硬合金製基体
２ＴｉＮ膜
３ＴｉＣＮ膜
４結合層
５Ａｌ_２Ｏ_３膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aluminum oxide coated tool for cutting and wear resistance.
[0002]
[Prior art]
In general, a coated tool is produced by forming a hard film on a substrate surface made of super hard alloy, high speed steel, or special steel by chemical vapor deposition (hereinafter referred to as CVD method) or physical vapor deposition. Such a coated tool has both the wear resistance of the coating and the toughness of the substrate, and is widely put into practical use. In particular, when cutting high-hardness materials at high speed, the cutting edge temperature of the cutting tool rises to around 1000 ° C, and it is necessary to withstand mechanical impacts such as wear and intermittent cutting due to contact with the work material at such high temperatures. Therefore, a coated tool having wear resistance, toughness, and heat resistance is useful. The hard film has a single layer or multiple layers of non-oxide film made of carbide, nitride, carbonitride of the periodic table 4a, 5a, 6a metal having excellent wear resistance and toughness or oxide film having excellent oxidation resistance. Used as a membrane. For example, TiC, TiN, and Ti (CN) are used for non-oxide films, and κ-type aluminum oxide (hereinafter referred to as κ-Al) is particularly used for oxide films. ₂ O ₃ Called. ) And α-type aluminum oxide (hereinafter α-Al) ₂ O ₃ Called. ) Is used. The disadvantage of the non-oxide film is that it is easily oxidized. In order to compensate for this disadvantage, it is possible to prevent oxidation of the non-oxide film by forming aluminum oxide having excellent oxidation resistance on these non-oxide films. Generally done. The disadvantage of this multilayer structure of non-oxide film / aluminum oxide film is that the adhesion between the non-oxide film and the aluminum oxide film is low, or the mechanical strength is not stable at high temperatures. Such α-Al ₂ O ₃ In order to eliminate the drawbacks of the film, in Japanese Patent Laid-Open Nos. 09-29512 and 08-276305, α-Al ₂ O ₃ It is disclosed that Ti (CNO) is used for the bonding layer serving as an underlayer of the layer, and the surface form of the bonding layer is equiaxed or needle-like crystal grains. Further, in Japanese Patent No. 3250134, Ti (CNO) is used as the underlayer of the aluminum oxide layer, and the surface state of the underlayer is made into sharpened needle crystals, thereby comprising an aluminum oxide layer and Ti (CNO). An example of improving the adhesion with the underlayer is disclosed. However, in the bonding layer made of Ti-based oxycarbonitride alone, α-Al ₂ O ₃ Protrusions that are expected to increase the adhesion to the film are difficult to form, and for this reason, α-Al is formed on the surface of the bonding layer throughout the chemical vapor deposition apparatus. ₂ O ₃ It was difficult to form a film with good adhesion. On the other hand, a bonding layer containing both Ti and Al has also been proposed as a bonding layer in which protrusions can be formed relatively easily. That is, in Japanese Patent Laid-Open No. 03-138368, α-Al is formed on a substrate made of a carbide bonded sintered body. ₂ O ₃ Layer and κ-Al ₂ O ₃ In the case of laminating layers, pure α-Al can be obtained by properly using two types of bonding layers (α transformation layer, κ transformation phase) made of (AlTi) (OC). ₂ O ₃ Layer and κ-Al ₂ O ₃ Examples have been disclosed that allow control of deposition with layers.
[0003]
[Problems to be solved by the invention]
However, since both the functions of the oxide film formation base due to the oxygen contained in these bonding layers and the anchor effect that enhances the adhesion by the protrusion structure are carried by one layer, for example, only the protrusion structure Α-Al by strengthening ₂ O ₃ Α-Al by further improving the adhesion of the binder layer or increasing the oxygen content of the bonding layer ₂ O ₃ However, it is difficult to make adjustments such as forming a stable film. In addition, in the bonding layer containing both Ti and Al, it is difficult to control the oxygen content. ₂ O ₃ Rather κ-Al ₂ O ₃ If the amount of oxygen is too large, the bonding layer itself becomes mechanically brittle, and α-Al ₂ O ₃ There is a drawback that it is easy to peel off. For example, in the current mass production type CVD apparatus, about 5000 insert tools are set in a range of an inner diameter of 260 mm and a height of 700 mm, and a film is formed. ₂ O ₃ In order to form a stable film, when the amount of oxygen is increased, a part of the apparatus becomes excessive in oxygen amount and α-Al ₂ O ₃ Tends to peel off, while α-Al ₂ O ₃ When the amount of oxygen is lowered to improve the adhesion of the steel, α-Al is added to some of the insert tools set in the CVD apparatus. ₂ O ₃ Is not deposited, and κ-Al ₂ O ₃ There is a drawback that the film is formed. Based on the above problems, the problem to be solved by the present invention is that α-Al is stable throughout the CVD apparatus and has excellent adhesion to the underlying non-oxide film. ₂ O ₃ It is an object to provide an aluminum oxide coated tool having excellent characteristics with little variation in quality.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have provided carbides, nitrides, carbonitrides, oxides, oxycarbides, oxynitrides, and oxycarbonitrides of Group 4a, 5a, and 6a metals in the periodic table on the substrate surface. An aluminum oxide-coated tool in which a single-layer film or a multilayer film composed of two or more kinds is formed, and an oxide film mainly composed of α-type aluminum oxide is formed on the surface of the film via a bonding layer In this case, the bonding layer is formed of Ti and Al oxides, oxycarbides, oxynitrides or oxycarbonitrides in order from the substrate side, and a Ti layer formed on the oxide film side mainly composed of α-type aluminum oxide. Oxidized by an oxide, oxycarbide, oxynitride or oxycarbonitride layer, and the bonding layer surface has a number of protrusions protruding substantially in the film thickness direction. Application of the present invention which is an aluminum coated tool Α-Al ₂ O ₃ The bonding layer between the main oxide film and the underlying non-oxide film is in a multi-layer structure, and each layer has a separate adhesion enhancement function and oxide film generation function by the anchor effect. Α-Al with excellent adhesion to the underlying non-oxide film ₂ O ₃ As a result, the above-mentioned problem is solved. Further, α-Al of the present invention ₂ O ₃ An oxide film mainly composed of α-Al of 80 vol% or more ₂ O ₃ And the rest is κ-Al ₂ O ₃ Γ-type aluminum oxide, θ-type aluminum oxide, δ-type aluminum oxide, χ-type aluminum oxide, and the like, which have a mixed structure composed of oxides of other structures such as aluminum oxide and zirconium oxide.
[0005]
First, α-Al is obtained by dividing the bonding layer into two layers. ₂ O ₃ Α-Al and the function to strengthen the adhesion to the oxide film mainly composed of ₂ O ₃ Α-Al which can be separated from the function that makes it easy to form and can control each function separately and has excellent adhesion to the underlying non-oxide film ₂ O ₃ Thus, an oxide film mainly composed of can be formed stably throughout the CVD apparatus. That is, the layer made of Ti and Al oxide, oxycarbide, oxynitride or oxycarbonitride is composed of a structure having a number of protrusions protruding substantially in the film thickness direction. Α-Al ₂ O ₃ It is possible to improve the adhesion of the oxide film mainly composed of Ti and form a layer made of Ti oxide, oxycarbide, oxynitride or oxycarbonitride on the surface side of the bonding layer, and optimize its oxygen content The α-Al in the entire CVD apparatus ₂ O ₃ Can be formed stably.
[0006]
Second, since the bonding layer contains a structure having a large number of protrusions protruding in the film thickness direction, the surface of the bonding layer also has a structure having a large number of protrusions protruding in the film thickness direction. In addition, as described above, the bonding layers are classified according to the film formation process, and when the film after film formation is observed, it is often impossible to clearly distinguish from the appearance. Also in this case, when an Al and Ti distribution was analyzed in the film thickness direction using an energy dispersive X-ray analyzer (hereinafter referred to as EDX) or an electron probe microanalyzer (hereinafter referred to as EPMA), Since a large amount of Al component is detected in a certain film thickness region and Al is hardly detected in other film thickness regions, it can be seen that the coupling layer is formed in the multilayer structure as described above. In particular, when the thickness of the bonding layer is several 100 nm and the bonding layer cannot be clearly analyzed for each layer, when the Al and Ti are linearly analyzed in the film thickness direction, the film thickness region has an Al / Ti ratio. It can be seen that the bonding layer is formed in the above-described layer shape by clearly increasing. When analyzing a small region of several tens of nanometers using EDX built in a transmission electron microscope (hereinafter referred to as TEM), Al, Ti, W, or the like excavated by ion milling or the like when a thin sample for TEM is prepared. , Co and other elements reattach to the TEM sample. At this time, Al and Ti reattach from the film, and W and Co reattach from the cemented carbide substrate. For this reason, the presence or absence of Al or Ti may not be clearly identified. Also at this time, it is found that the bonding layer is formed in the above-described layer shape by analyzing the Al / Ti ratio at different positions in the film thickness direction as described above. In this case, the amount of Al / Ti ratio detected by adhesion at the time of TEM sample preparation, that is, the zero point of the Al / Ti ratio, measures the Al / Ti ratio of the base non-oxide film that originally does not contain Al such as TiCN. Can be obtained.
[0007]
Thirdly, according to the present invention, the bonding layer is a layer composed of an oxide of Ti, an oxycarbide or an oxynitride in order from the substrate side, an oxide of Ti and Al, an oxycarbide, an oxynitride or an oxycarbonitride. And a layer made of Ti oxide, oxycarbide, oxynitride or oxycarbonitride. A second layer containing Ti, Al, and oxygen is formed on the underlying non-oxide film through a first layer made of a film containing Ti and oxygen, thereby forming a gap between the underlying non-oxide film and the second layer. Adhesion is further enhanced, and higher adhesion is obtained between the bonding layer and the base non-oxide film. Further, as a film forming gas, a second layer having a large number of protrusions protruding substantially in the film thickness direction with a smaller oxygen gas supply amount can be stably formed, and the second layer has a high mechanical strength and an upper layer. The adhesion with the oxide film is further improved, and a coated tool having further excellent tool characteristics can be obtained.
[0008]
Fourthly, in the present invention, a large number of protrusions protruding in the substantially film thickness direction on the surface of the bonding layer are bent in a bowl shape. By bending it into a saddle shape, the bonding layer and α-Al ₂ O ₃ Higher adhesion can be obtained with an oxide film mainly composed of the above, and a coated tool having further excellent tool characteristics can be obtained.
[0009]
Fifth, in the present invention, the tips of many protrusions protruding in the substantially film thickness direction on the surface of the bonding layer are rounded. The rounded tip means that the tip is not sharp but is formed with a gentle curved surface. The sectional area of the tip of the protrusion is increased, the mechanical strength of the protrusion itself is increased, and the bonding layer and α-Al ₂ O ₃ Higher adhesion can be obtained with an oxide film mainly composed of the above, and a coated tool having further excellent tool characteristics can be obtained.
[0010]
Sixth, according to the present invention, since the cross section of at least a part of the bonding layer is formed of crystal grains elongated in a direction substantially perpendicular to the substrate, the surface of the bonding layer is rich in protrusions, and α- Al ₂ O ₃ It is possible to further improve the adhesion of the oxide film mainly composed of. It can be confirmed by observing with SEM or TEM that the cross section of the layer is composed of crystal grains elongated in a direction substantially perpendicular to the substrate.
[0011]
Seventh, the present invention provides α-Al ₂ O ₃ Single-layer coating of any one of nitride, carbide, carbonitride, oxide, oxynitride, oxycarbide and oxycarbonitride of at least colored Ti, Zr or Hf on the surface of the oxide film mainly containing Or a multi-layer coating consisting of two or more types is formed, the slidability of the tool surface is further increased, and further excellent tool properties are obtained, and the outer layer portion of the tool is composed of a colored coating and used as a tool It becomes possible to easily determine whether or not it has been completed.
[0012]
Eighth, in the present invention, at least a part of the outermost layer around the blade edge portion is removed after the formation of the film, and α-Al ₂ O ₃ By exposing the oxide film mainly composed of α-Al, at least one part of the blade edge part having high contact frequency with the work material is particularly excellent in oxidation resistance and welding resistance. ₂ O ₃ Therefore, it is possible to realize particularly excellent cutting durability characteristics because the welding with the work material is particularly reduced.
[0013]
A known film forming method can be applied to the coating method in the present invention. For example, a normal thermal chemical vapor deposition method, a chemical vapor deposition method with plasma added, or the like can be used. Applications are not limited to cutting tools, α-Al ₂ O ₃ It is also possible to use a wear-resistant material, a mold, a molten metal part, or the like covered with a single-layer or multilayer hard film containing an oxide film mainly composed of. The oxide film is α-Al ₂ O ₃ Not limited to a single layer, α-Al ₂ O ₃ Other oxides such as α-Al ₂ O ₃ And κ-Al ₂ O ₃ Mixed film with γ-type aluminum oxide, θ-type aluminum oxide, δ-type aluminum oxide, χ-type aluminum oxide, etc., or α-Al ₂ O ₃ Similar effects can be obtained even with a mixed film of aluminum and other oxides such as zirconium oxide. Next, although the coated tool of this invention is demonstrated concretely by an Example, this invention is not limited by these Examples.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
As Example 1 of the present invention, first, a cemented carbide substrate for a cutting tool having a JIS standard CNMG120408 shape having a component composition of WC: 72% by mass, TiC: 8% by mass, (TaNb) C: 11% by mass, and Co: 9% by mass. Carbon trays having an inner diameter of 260 mm and a height of 25 mm, in which 200 pieces were uniformly set, were stacked in 23 stages in the vertical direction and set in a CVD reactor. In order to ensure the stability of the film formation, two and three dummy trays were set above and below the effective 23-stage tray, respectively. And H ₂ Carrier gas and TiCl ₄ Gas and N ₂ After forming a 0.5 μm thick TiN film at 900 ° C. using a gas as a source gas, ₂ Carrier gas and TiCl ₄ Gas, N ₂ Gas, CH ₃ After forming a 6 μm-thick TiCN film at 890 ° C. using CN gas as the source gas, H at 1000 ° C. ₂ Carrier gas and TiCl ₄ Gas, CH ₄ Gas, N ₂ A Ti (CN) film was formed for 15 minutes using gas as a source gas. After that, CO gas and AlCl were added to the gas group having the same structure as that used for the film formation of Ti (CN). ₃ (TiAl) (CNO) film was formed at 1000 ° C. for 10 minutes by adding gas, ₂ Carrier gas and TiCl ₄ Gas, CH ₄ Gas, N ₂ Gas and CO ₂ A Ti (CNO) film was formed for 7 minutes using a gas and a CO gas as source gases to form a bonding layer composed of two layers of (TiAl) (CNO) and Ti (CNO). Then H ₂ Carrier gas, AlCl ₃ Gas, CO ₂ 4 μm thick Al using gas as source gas ₂ O ₃ A film is formed at 1020 ° C., and H ₂ Carrier gas and HfCl ₄ Gas and N ₂ An HfN film having a thickness of 1 μm was formed at 1050 ° C. using a gas as a source gas, and then cooled to room temperature. Next, the periphery of the honing portion of the cutting edge portion of the sample taken out from the CVD apparatus is polished with a rubber grindstone, so that the inner layer of Al ₂ O ₃ The film was exposed to produce the oxide film-coated tool of the present invention.
[0015]
As a result of measuring the X-ray diffraction pattern by the 2θ-θ scanning method with the X-ray diffractometer (RU-200BH) manufactured by Rigaku Denki Co., Ltd. using the CuKα1 line as the X-ray source, The inner and outer sample numbers of the upper 23rd stage are 23A and 23B, the inner and outer sample position numbers of the middle 12th stage are 12A and 12B, and the inner and outer sample position numbers of the lowermost first stage are 1A and 1B. The sample set at any position of α-Al ₂ O ₃ Only the X-ray diffraction peak of κ-Al was detected. ₂ O ₃ Etc. The peak intensity was below the detection limit. From this, α-Al is added to the entire sample in the effective tray. ₂ O ₃ Is considered to have been formed.
[0016]
An example of the present invention is tilted by 17 degrees and polished from the substrate surface to α-Al ₂ O ₃ FIG. 1 shows a photomicrograph of the film up to 1000 × magnification, and FIG. 2 shows a schematic diagram thereof. 1 and 2, a TiN film 2 and a Ti (CN) film 3 are formed on the surface of a cemented carbide substrate 1, and α-Al is formed thereon via a bonding layer 4. ₂ O ₃ It is shown that a film 5 is formed. 1 and 2, a large number of protrusions from the surface of the bonding layer 4 are α-Al. ₂ O ₃ Α-Al protruding to the membrane 5 side ₂ O ₃ It can be seen that the film 5 bites into the film 5. FIG. 3 shows the bonding layer 4 and α-Al of the above sample. ₂ O ₃ FIG. 4 is a schematic view of the vicinity of the interface between the films 5 taken by SEM at a magnification of 5000 times. 3 and 4, the surface of the bonding layer) has a large number of protrusions protruding substantially in the film thickness direction, and the tip is bent in a bowl shape, particularly the third and right from the left in FIGS. It can be seen from the third protrusion. It can also be seen that the tips of these protrusions are not sharp but round.
[0017]
After the film cross section of the film formation surface of the example of the present invention was polished to a thickness of 20 μm or less, the thickness of the film cross section was extremely reduced by ion milling to prepare a sample for TEM observation. Then, using TEM (H-800) manufactured by Hitachi, Ltd., Ti (CN) film part and Al under the condition of acceleration voltage 200 kV ₂ O ₃ After identifying the thin bonding layer portion between the membrane portions, elemental analysis was performed using ERAN manufactured by NORAN with built-in TEM. As a result, the bonding layer could be separated into two layers, the first layer on the substrate side was Ti and Al, It was found that the two layers were formed only from Ti. Note that light elements C, N, and O could not be analyzed for EDX analysis. In addition, in order to determine the amount of redeposits generated during the preparation of the TEM sample, the amount of W, Co, and Al at the center of the TiCN film directly under the bonding layer ₂ O ₃ Ti and Al amounts were measured at the central portion of the HfN film immediately above the film, and the values were subtracted from the analysis value of the bonding layer portion as the amount of reattachment. Further, as a result of the TEM observation, the film thickness region with a large amount of Al in the bonding layer is formed by crystal grain groups whose cross section is elongated in the film thickness direction, and a part thereof protrudes in the film thickness direction and has protrusions. In addition, it was observed that there was a film thickness region in which Ti was analyzed on the surface of the bonding layer but Al was analyzed only for the amount of the reattachment, and this region was formed from granular crystal grains.
[0018]
(Example 2)
As Example 2 of the present invention, first, a substrate having the same material and shape as Example 1 of the present invention was placed in a CVD reactor in the same manner as Example 1, and a TiN film and two types of Ti ( CN) film was formed. After that, CO gas was added to the gas group having the same configuration as that used for the second Ti (CN) film formation to form a Ti (CNO) film at 1000 ° C. for 15 minutes, and then further AlCl. ₃ A gas was added to form a (TiAl) (CNO) film for 10 minutes, and more H ₂ Carrier gas and TiCl ₄ Gas, CH ₄ Gas, N ₂ Gas and CO ₂ A Ti (CNO) film is formed for 7 minutes by using gas and CO gas as source gases, thereby forming a bonding layer composed of three layers of Ti (CNO)-(TiAl) (CNO) -Ti (CNO). did. Thereafter, Al under the same conditions as Example 1 of the present invention. ₂ O ₃ After filming, further H ₂ Carrier gas and CH ₄ Gas, N ₂ Gas and ZrCl ₄ A Zr (CN) film having a thickness of 1 μm was formed at 1020 ° C. using gas as a source gas, and then cooled to room temperature. Next, the periphery of the honing portion of the cutting edge portion of the sample taken out from the CVD apparatus is polished with diamond abrasive grains and a brush to thereby form an inner layer of Al. ₂ O ₃ The film was exposed to produce Inventive Example 2. As a result of measuring the X-ray diffraction patterns of Example 2 of the present invention in the same manner as in Example 1 of the present invention, the samples at sample position numbers: 23A, 23B, 12A, 12B, 1A and 1B were all α-Al ₂ O ₃ Only the X-ray diffraction peak of κ-Al was detected. ₂ O ₃ Etc. The peak intensity was below the detection limit. Similar to Example 1 of the present invention, α-Al was added to the entire sample in the effective tray. ₂ O ₃ Was deposited. Moreover, as a result of observing the polished surface of Invention Example 2 with an optical microscope and SEM in the same manner as in Invention Example 1, many protrusions protrude in the film thickness direction on the surface of the bonding layer, and many of the tips are formed. It was confirmed that it was bent into a saddle shape and the tip of the protrusion was rounded. As a result of analyzing the film cross section of the film formation surface of Invention Example 2 by TEM-EDX as in Invention Example 1, the bonding layer can be separated into three layers, the first layer on the substrate side is Ti only, and the second layer is It was found that Ti and Al and the third layer were formed only from Ti. The light elements C, N, and O could not be analyzed in the same manner as Example 1 of the present invention. The first layer of the bonding layer is formed of granular crystal grains, and the second layer is formed of crystal grains whose cross section is elongated in the film thickness direction, and one part thereof forms protrusions in the film thickness direction. It was observed that the third layer was again formed of granular crystal grains.
[0019]
(Example 3)
As Comparative Example 3, first, α-Al due to the difference in structure of the bonding layer. ₂ O ₃ In order to elucidate the influence on the adhesion and cutting characteristics of the oxide film mainly composed of the substrate, a substrate having the same material and shape as in the present invention example 1 was installed in the CVD reactor as in the present invention example 1, A TiN film and two types of Ti (CN) films were formed under the same conditions as in Invention Example 1. Then H ₂ Carrier gas and TiCl ₄ Gas and CH ₄ After forming a TiC film by reacting at 1010 ° C. for 5 to 30 minutes using a gas as a source gas, TiCl is used as it is. ₄ Gas and CH ₄ Stop gas and H ₂ Carrier gas and CO ₂ A bonding layer was prepared by flowing a gas for 15 minutes to oxidize the surface of the TiC film already formed. Thereafter, Al having a thickness of 4 μm under the same conditions as Example 1 of the present invention. ₂ O ₃ A film and a 1 μm thick HfN film were formed and then cooled to room temperature to produce Comparative Example 3. As a result of measuring the X-ray diffraction pattern of Comparative Example 3 in the same manner as in Example 1 of the present invention, the samples at the sample position numbers: 23A, 23B, 12A, 12B, 1A, 1B, all α-Al ₂ O ₃ Only the X-ray diffraction peak of κ-Al was detected. ₂ O ₃ Etc. The peak intensity was below the detection limit. Α-Al on the entire sample in the effective tray ₂ O ₃ Is considered to have been formed. As a result of observing the polished surface of Comparative Example 3 with an optical microscope and SEM, the surface of the bonding layer was formed of granular crystal grains and formed a gentle curved surface, and the projections as in Invention 1 and Invention Example 2 Was found not formed. As a result of observing the film cross section of Comparative Example 3 with TEM, TiN, Ti (CN), TiC, bonding layer, Al in order from the substrate surface. ₂ O ₃ It was found that each of the layers was formed, and that the bonding layer was composed of granular crystal grains and was not composed of elongated crystal grains in the film thickness direction. Moreover, as a result of analyzing the composition of the bonding layer by EDX, only Ti was detected and Al was detected only for the amount of redeposition, and the bonding layer contained only Ti as a metal component and did not contain Al. all right.
[0020]
Example 4
As Comparative Example 4, α-Al due to the difference in structure of the bonding layer ₂ O ₃ In order to clarify the influence on the stable film-forming property and the cutting characteristics of the oxide film mainly composed of the above in the CVD apparatus, a substrate having the same material and shape as the present invention example 1 is formed by CVD as in the present invention example 1. The TiN film and two types of Ti (CN) films were formed under the same conditions as in the first example of the present invention. After that, CO gas and AlCl were added to the gas group having the same structure as that used for the film formation of Ti (CN). ₃ (TiAl) (CNO) film was formed for 10 minutes by adding gas. 4 μm-thick Al directly under the same conditions as Example 1 of the present invention, directly on the surface of the bonding layer comprising the (TiAl) (CNO) single layer. ₂ O ₃ A HfN film having a thickness of 1 μm was formed. And by polishing the periphery of the honing part under the same conditions as Example 1 of the present invention, the inner layer of Al ₂ O ₃ Comparative Example 4 was prepared by exposing the film. As a result of measuring the X-ray diffraction pattern of Comparative Example 4 using the same method as in Example 1 of the present invention, the sample position numbers: 23A, 23B, 12A, 12B, 1A, 1B, the sample position numbers: 23A, 23B, 12A, 1B Sample of α-Al ₂ O ₃ Only the X-ray diffraction peak of κ-Al was detected. ₂ O ₃ Although the peak intensities of the samples were below the detection limit, the samples of sample position numbers: 12A and 1A were κ-Al ₂ O ₃ The peak of ₂ O ₃ The (104) peak was only weakly detected. It can be seen that Comparative Example 4 cannot stably produce an oxide film mainly composed of α-type aluminum oxide. As a result of observing the polished surface of Comparative Example 4 with an optical microscope and SEM, a large number of protrusions protrude in the film thickness direction on the surface of the bonding layer, but the tips of these protrusions are sharp and not round. confirmed. As a result of TEM observation of the film cross section of the film formation surface of Comparative Example 4 under the same conditions as Example 1 of the present invention, the bonding layer is composed of a single layer containing both Ti and Al, and a second layer consisting of only Ti is formed thereon. It was found that no layer was formed.
[0021]
Next, using each of the five cutting tools manufactured under the conditions of Invention Example 1 and Invention Example 2 and the tools manufactured under the conditions of Comparative Examples 3 and 4, the following cutting conditions were continued for 1 minute and 10 minutes. After the cutting test, the peeling state of the aluminum oxide film was observed and evaluated with an optical microscope having a magnification of 200 times. Cutting specifications are: work material: FCD700, cutting speed: 300 m / min, feed: 0.3 mm / rev, cutting: 2.0 mm, use of water-soluble cutting oil. As a result of this cutting test, in Comparative Example 3, the aluminum oxide film on the rake face was largely peeled after cutting for 1 minute, whereas in Invention Example 1, Invention Example 2 and Comparative Example 4, all were cut for 1 minute continuously. No peeling of the aluminum oxide film was observed, and it was found that the adhesion of the aluminum oxide film to the base film was excellent. Further, when the present invention 1 and 2 and comparative example 4 were observed after continuous cutting for 10 minutes, κ-Al ₂ O ₃ In the sample of Comparative Example 4 where the X-ray diffraction peak of No. 12B and No. 12B of Sample No. 12B and 1B had a large crack in the aluminum oxide film on the rake face, the film was largely peeled off in some places. Observed. This is because the surface temperature of the film increases by continuous cutting for 10 minutes, and κ-Al ₂ O ₃ Part of α-Al ₂ O ₃ It is considered that cracks were generated because the volume was shrunk and the volume contracted, and the film was peeled off starting from the cracks. Then, as a result of continuous cutting of the remaining sample for 10 minutes, the sample position numbers: 23A, 23B, 12A, and 1B of Comparative Example 4 had the rake face peeled off, whereas the present invention example 1 and the present invention example No sample 2 peeled off. It can be seen that in Invention Example 1 and Invention Example 2, an aluminum oxide film having excellent adhesion to the base film and excellent heat resistance and crack resistance is formed throughout the CVD apparatus.
[0022]
【The invention's effect】
As described above, according to the present invention, α-Al has excellent adhesion to the underlying non-oxide film. ₂ O ₃ As a result, there is little variation in quality, excellent adhesion between multilayer films, heat resistance and crack resistance, and excellent tooling. An excellent aluminum oxide coated tool having characteristics and a long tool life can be realized.
[Brief description of the drawings]
FIG. 1 shows a structure photograph of an example of the present invention.
FIG. 2 shows a schematic diagram of FIG.
FIG. 3 shows the coupling film of FIG. 1 and α-Al. ₂ O ₃ The structure photograph of the interface vicinity between films is shown.
FIG. 4 shows a schematic diagram of FIG. 3;
[Explanation of symbols]
1 Cemented carbide substrate
2 TiN film
3 TiCN film
4 bonding layers
5 Al ₂ O ₃ film

Claims

Single layer film or two kinds of carbides, nitrides, carbonitrides, oxides, oxycarbides, oxynitrides and oxycarbonitrides of Group 4a, 5a, and 6a metals of the periodic table on the substrate surface In the aluminum oxide-coated tool in which a multilayer coating composed of the above is formed and an oxide film mainly composed of α-type aluminum oxide is formed on the surface of the coating via a bonding layer, the bonding layer is formed of Ti and at least in order from the substrate side. Ti oxide, oxycarbide, oxynitride or oxycarbonitride formed on a layer made of Al oxide, oxycarbide, oxynitride or oxycarbonitride and an oxide film mainly composed of α-type aluminum oxide An aluminum oxide-coated tool characterized in that it is composed of a layer made of a material, and the surface of the bonding layer has a number of protrusions protruding substantially in the film thickness direction.

2. The coated tool according to claim 1, wherein the bonding layer is at least a layer composed of an oxide of Ti, an oxycarbide or an oxynitride in order from the substrate side, an oxide of Ti and Al, an oxycarbide, an oxynitride or an oxycarbonitride. An aluminum oxide-coated tool comprising three layers: a layer made of a material and a layer made of an oxide of Ti, an oxycarbide, an oxynitride, or an oxycarbonitride.

The coated tool according to claim 1 or 2, wherein the protrusion on the surface of the bonding layer is bent in a bowl shape.

The coated tool according to any one of claims 1 to 3, wherein a tip of the protrusion is rounded.

The coated tool according to any one of claims 1 to 4, wherein a cross section of at least a part of the bonding layer is formed of crystal grains elongated in a substantially film thickness direction.

6. The coated tool according to claim 1, wherein at least one of a nitride, carbide, or carbonitride of Ti, Zr, or Hf is formed on the surface of the oxide film mainly composed of α-type aluminum oxide. A single layer coating or a multilayer coating consisting of two or more types is formed.